6 divided by 812 is very difficult to do without using a calculator - I would suggest the bus shelter method, as I've shown in the photo attached, but it is still quite difficult to use that method without a calculator.
If, however, you mean 812 divided by 6, that is a lot easier to calculate using the bus shelter method - so, just in case, I've attached the method for that too.
6 divided by 812 = 0.007389...